1. Field of the Invention
This invention relates to an exhaust system for a sideways-mounted engine having a pair of cylinder rows such as a V-type engine which has a pair of cylinder rows and is mounted sideways so that the cylinder rows are arranged side by side in the longitudinal direction of the vehicle body.
2. Description of the Prior Art
When an engine having a pair of cylinder rows such as a V-type engine or a horizontally opposed engine is mounted sideways on a vehicle body, the cylinder rows are opposed to each other in the longitudinal direction of the vehicle body. Accordingly, though an exhaust pipe which is connected to the rearward cylinder row on the rear side thereof may be simply led rearward, an exhaust pipe which is connected to the forward cylinder row on the front side thereof must be led rearward across the engine body, which makes difficult layout of the exhaust pipe.
As disclosed, for instance, in Japanese Unexamined Utility Model Publication No. 62(1987)67920, there has been proposed an exhaust system in which a recess is formed on the lower surface of an oil pan of the engine, the exhaust pipes for the forward and rearward cylinder rows are jointed together in the recess and a common exhaust pipe is connected to the junction of the exhaust pipes and extends rearward. In this engine, by jointing the exhaust pipes in the recess of the oil pan, a compact layout of the exhaust pipes is realized and a large road clearance is obtained.
When the V-type engine or the horizontally opposed engine is mounted sideways, it is preferred that the exhaust pipes for the forward and rearward cylinder rows be as long as possible in order to prevent exhaust interference between the cylinders and be equal to each other in order to equalize exhaust resistance.
The conventional exhaust system described above where the exhaust pipes for the respective cylinder rows are jointed in the recess formed in the oil pan just below the engine is disadvantageous in that the lengths of the respective exhaust pipes, i.e., the lengths between the junction of the respective exhaust pipes and the junctions of the respective exhaust pipes to the respective cylinder rows cannot be sufficiently long, and accordingly, exhausts of the different cylinders interfere with each other to greatly increase the exhaust resistance at the junction of the respective exhaust pipes.